Lapping tool



May 4 1926. 1,583,010

H. RICHARDSON LAPPING TOOL Filed March 18, 1925 I 1,583,010 UNITED STATES PATENT OFFICE.

HENRY RICHARDSON, OF WALTHAM, MASSAGIEIIII'SE'I." I.S.

LAPPING TOOL.

ime, filed March 18,1925. Serial m). 16,368.

To all whom it may concem:

Be it known that I, HENRY RICHARDSON,

a citizen of the United States, residing at Waltham, in the county of Middlesex and State of Massachusetts, have invented new and useful Improvements in Lapping Tools, of which the following is a specification.

This invention relates to a lapping tool adapted to grind a cylindrical internal. surface, such as thatof a cylinder of an internal combustion engine, the tool includinga' cylindrical lap, formed to fit a cylindrical internal surface to be ground, and adapted to carry on its periphery granular 'or powdered abrasive material.

The invention is embodied in a tool ineluding a tubular lap of inelastic soft metal,

externally cylindrical and internally tapered and adapted to be stretched to compensate for wear of its periphery, and adjustable lap-holding, rotating and stretching means, adapted to stretch the lap when its external diameter has been reduced by wear, and thus compensate for such reduction, the lap presenting a continuous cylindrical periphery, adapted to cooperate advantageously with the abrasive material.

, Of the accompanying drawings forming a part of this specification,

Figure 1 is an end View of a tool eIn-- is a lap 12, composed of inelastic soft metal,

such as lead, or an alloy thereof, and is adapted to be stretched by internal pressure, the periphery of the lap being continuous or uninterrupted.

The lap is externally cylindrical, its periphery being of uniform diameter from I end to end, and is internally tapered to cooperate with adjustable la -holding, rotating, and stretching means a apted to stretch the lap to increase its external diameter, after the latter has been reduced by wear, and thus compensate for such reduction, and

permit the maintenance of a predetermined diameter.

In the embodiment shown" by Figures'l, 2 and 3, the lap 12 embraces and is movable endwise on a plug which includes an outer member 13, externally tapered to coni form to the internal taper of the lap, and

an inner member 14, externally. tapered to conform to the internal taper of the outer member. -Said members are formed to be intcrengaged, so that the inner member is rotated by any suitable means. The spindle is provided with a screw thread 17, at its inner end portion.

Mounted movably on the threaded. portion of the spindle is a hollow cup-shaped follower 18, the cavity of which is formed to surround a portion of the plu as shown by Figure 3, the outer end of t e follower being formed to bear on the inner end of the lap 12. spindle thread, backs the follower, and is adapted to exert pressure on the lap through the follower in the direction required to move the lap outward, endwise from the position shown by Figure 2, to that shown by Figure 3, and to various other positions.

The arrangement of the tapered internal surface of the lap, and the tapered external surface of the plug is such that an outward movement of the lap stretches the latter and increases its diameter to an extent determined by the extent of the outward movement. 1

Vhen the lap 12 is unworn, it may be in the position shown by Figure 2, its external diameter being supposed to be suflicient 1'10 cooperate properly with an internal surface to be ground. To the periphery of the lap is applied a suitable granular abrasive held in contact with the sleeve by oil. The continuous or uninterrupted periphery of the lap prevents any of the abrasive materlal from sinking within the periphery, so that 1 A nut 19 engaged with the the entire periphery is utilized to support said material.

When the e'xternaldiameter of the lap 1s reduced by wear, the nut and follower are adjusted to the left from the posit on shown by Figure 2, until the lap is stretched to the redetermined external diameter. The adustment may be repeated until the lap wall becomes too thin for further use, the lap being then removed and replaced by a new one. In case the ressure of the-lap against the plug is not su' cient to cause a frictional engagement between said parts, SllfllC-lBllt to cause the rotation of the lap by the plug, the external surface of the plug may be positively interengaged with the internal surface of the lap, as by longitudinal ribs 21, formed onthe plug, and longitudinal grooves 22, formed in the lap, as shown by Figure 1, and by dotted lines in Figure 2. The twopart plug shown by Figures 1, and 3, is preferred, when the lap is of relatlvely large diameter. When the lap is smaller, the outer member 13- may be omitted, as shown by Figures 4 and 5, the lap being tapered internally to conform to the tapered external surface of the core provided by the member 14:.

The tapered external surface of the plug increases in size from its inner to its outer end, and the outer end of the plug 15 unobstructed, so that the outer end of the lap may project therefrom, as shown by Figure 3. Owing to the fact that the periphery of the lap is continuous or uninterrupted, said periphery is not distorted or caused to deviate from a true cylindrical form by the expansion of the lap.

I claim:

1. A lapping tool comprisinga tubular lap of soft inelastic metal, having an uninterrupted periphery and externally cylindrical and internally tapered, the lap being adapted to be stretched to compensate for wear of its periphery, and adjustable lapholding, rotating and stretching means.

adapted to stretch the la when its external diameter has been reduce by wear.

2. A lapping tool comprising a rotatable plug, having atapered external surface increasing in size from its inner to its outer end, the latter being unobstructed, an. ex ternally cylindrical and internally ta ered tubular lap of soft inelastic metal em bracing the plug and adapted to be stretched, the lap having an uninterrupted periphery,

the tapered internal surface of the lap conforming to the tapered external surfaceof the plug, and means for moving the lap endwise on the plug from the inner to the outer end of the latter to stretch the lap and compensate for wear of its cylindrical periphery, the unobstructed outer end of the plug permitting the projection of the outer end of the lap from the plug.

3. A lapping tool comprising a rotatable plug, havinga tapered external surface, and provided with a screw-threaded spindle coaxial with ,the plug, an externally cylindrical and internally tapered lap of soft inelastic metal embracing the plug and adapted to be stretched, the-tapered internal surface. of the lap conforming to the tapered external surface of the plug, a hollow follower mounted on the spindle and formed to bear on the inner end of the lap and surround the inner end portion of the plug,

and a nut engaged with the threaded spindle member, said members having unobstructed outer ends and being interengaged to cause rotation of the outer member by the inner member, an externally cylindrical and internally tapered lap of soft inelastic metal embracing the .outer member and adapted to be stretched, the lap having an uninter rupted periphery, and means carried by the spindle for moving the lap endwise on the plug to stretch the lap and compensate for wear of its cylindrical periphery.

5. As an article of manufacture, a tubular.

lap externally cylindrical and internally tapered, and made of soft inelastic metal, and adapted to be stretched by internal pressure to compensate for wear of its cylindrical periphery, said periphery being uninterrupted, so that it forms a continuous cylindrical surface adapted to carry granular abrasive material applied thereto.

In testimony whereof I have affixed my signature.

HENRY RICHARDSON. 

